Lithium-rich manganese-based composite material, preparation method thereof, and positive electrode sheet and secondary battery

Abstract

This application relates to the field of electrode active materials technology, and provides a lithium-rich manganese composite material with LiNi as the main phase. a M b O2 and cLi2O·dLi as a secondary phase x Mn y O z Secondary phases are doped into the main phase; among them, LiNi a M b In O2, 0.6 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.40, M is the metal element contained in the ternary active material, cLi2O·dLi x Mn y O z In the formula, 0.01≤c≤0.2, 0.5≤d≤4.5, 0.5≤x≤5.5, 0.2≤y≤2.2, 0.8≤z≤6.8. The lithium-rich manganese composite material provided in this application not only functions as a lithium replenishment additive, improving the initial coulombic efficiency of the battery, but also, after delithiation, forms a ternary active material with the main phase, endowing the lithium-rich manganese composite material with advantages such as high energy density, high capacity retention, and stable lithium replenishment and cycle performance.

Description

Technical Field

[0001] This application belongs to the field of electrode active material technology, and particularly relates to a lithium-rich manganese composite material, its preparation method, positive electrode sheet, and secondary battery. Background Technology

[0002] With the rise of the new energy industry, the new energy industry chain is paying increasing attention to raw materials. Lithium-ion battery material technology is being updated rapidly, and the development of high-quality ternary precursors and cathode materials has always been a hot topic in new energy materials. In order to further improve the energy density of materials, there is a general trend in the market to develop high-nickel cathode materials, among which, research on high-nickel ternary precursors and their cathode materials is relatively more extensive.

[0003] Currently disclosed high-nickel ternary cathode materials (NCMs) possess high electrode potential, good electronic conductivity, and are one of the application directions for high-energy-density lithium batteries. Furthermore, the three elements exhibit a good synergistic effect.

[0004] However, in practical applications, it has been found that the high-nickel ternary materials currently reported also have certain defects, such as poor cycle performance, low capacity retention, and poor thermal stability, which lead to unsatisfactory safety and storage performance. Summary of the Invention

[0005] The purpose of this application is to provide a lithium-rich manganese composite material, its preparation method, a positive electrode sheet, and a secondary battery, aiming to solve the technical problems of unsatisfactory cycle performance and capacity retention of existing high-nickel ternary materials.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a lithium-rich manganese composite material, which includes LiNi as the main phase. a M b O2 and cLi2O·dLi as a secondary phase x Mn y O z Secondary phases are doped into the main phase; among them, LiNi a M b In O2, 0.6 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.40, M is the metal element contained in the ternary active material, cLi2O·dLi x Mn y O z In the equation, 0.01≤c≤0.2, 0.5≤d≤4.5, 0.5≤x≤5.5, 0.2≤y≤2.2, and 0.8≤z≤6.8.

[0008] Secondly, this application provides a method for preparing lithium-rich manganese composite materials, comprising the following steps:

[0009] According to the main phase LiNi a M b Ni, M (represented by the element), and cLi₂O·dLi in O₂ x Mn y O z The stoichiometric ratio of Mn in the solution provides a nickel source, a manganese source, and a metal source containing said M;

[0010] The nickel source, the manganese source, the M-containing metal source, and the lithium source are mixed to obtain a ternary precursor containing manganese and nickel.

[0011] A ternary precursor containing manganese and nickel was sintered in a protective atmosphere and then ground with Li2O to obtain a lithium-rich manganese composite material.

[0012] Thirdly, this application provides a positive electrode sheet, including a positive current collector and a positive active layer bonded to the surface of the positive current collector, wherein the positive active layer contains a lithium-rich manganese composite material provided in this application or a lithium-rich manganese composite material prepared by the preparation method of the lithium-rich manganese composite material provided in this application.

[0013] Fourthly, this application provides a secondary battery, including a positive electrode and a negative electrode, wherein the positive electrode is the positive electrode provided in this application.

[0014] Compared with the prior art, this application has the following technical effects:

[0015] The lithium-rich manganese composite material provided in the first aspect of this application contains manganese in the form of a secondary phase cLi₂O·dLi. x Mn y O z In its existing form, it not only acts as a lithium replenishing additive, supplementing the lithium ions consumed during the formation of the SEI film in the first charge-discharge process and improving the battery's initial coulombic efficiency, but also possesses ultra-high irreversible capacity, structural stability, and safety, giving the composite material excellent lithium replenishment performance. Furthermore, the secondary phase cLi₂O·dLi x Mn y O z After delithiation, the manganese oxide in this secondary phase reacts with the LiNi in the main phase. a M b O2 forms a ternary active material, endowing the lithium-rich manganese composite material of this application with the activity of a ternary active material while having good lithium replenishment effect. This gives the lithium-rich manganese composite material advantages such as high energy density, high capacity retention, good lithium replenishment stability, and stable cycle performance.

[0016] The method for preparing lithium-rich manganese-based composite materials provided in the second aspect of this application involves first mixing a nickel source, a manganese source, a metal source containing M, and a lithium source to obtain a manganese-nickel ternary precursor. Then, the manganese-nickel ternary precursor is sintered in a protective atmosphere, followed by grinding with Li₂O to obtain the lithium-rich manganese-based composite material. This preparation method is simple, easy to control, low-cost, and suitable for large-scale production. Furthermore, the resulting lithium-rich manganese-based composite material exhibits good uniformity, high energy density, high capacity retention, good lithium replenishment stability, and stable cycle performance.

[0017] The positive electrode provided in the third aspect of this application contains the lithium-rich manganese composite material provided in this application, or the lithium-rich manganese composite material prepared by the preparation method of the lithium-rich manganese composite material provided in this application. Therefore, the positive electrode of this application has high energy density, lithium replenishment function, high cycle performance and long life.

[0018] The secondary battery provided in the fourth aspect of this application, due to the presence of the electrode sheet of this application, has excellent first coulombic efficiency, high energy density and cycle performance, high capacity retention, long life, and stable electrochemical performance. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating the preparation method of the lithium-rich manganese composite material provided in the embodiments of this application. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0024] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0027] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0028] A first aspect of this application provides a lithium-rich manganese-based composite material, which includes LiNi as the main phase. a M b O2 and cLi2O·dLi as a secondary phase x Mn y O z Secondary phases are doped into the main phase; among them, LiNi a M bIn O2, 0.6 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.40, M is the metal element contained in the ternary active material, cLi2O·dLi x Mn y O z In the equation, 0.01≤c≤0.2, 0.5≤d≤4.5, 0.5≤x≤5.5, 0.2≤y≤2.2, and 0.8≤z≤6.8.

[0029] The lithium-rich manganese composite material provided in this application contains manganese in the form of a secondary phase cLi₂O·dLi. x Mn y O z In its existing form, it not only acts as a lithium replenishing additive, supplementing the lithium ions consumed during the formation of the SEI film in the first charge-discharge process and improving the battery's initial coulombic efficiency, but also possesses ultra-high irreversible capacity, structural stability, and safety, giving the composite material excellent lithium replenishment performance. Furthermore, the secondary phase cLi₂O·dLi x Mn y O z After delithiation, the manganese oxide in this secondary phase reacts with the LiNi in the main phase. a M b O2 forms a ternary active material, endowing the lithium-rich manganese composite material of this application with the activity of a ternary active material while having good lithium replenishment effect. This gives the lithium-rich manganese composite material advantages such as high energy density, high capacity retention, good lithium replenishment stability, and stable cycle performance.

[0030] In the embodiment, the main phase LiNi a M b In O2, M does not contain manganese. Therefore, the secondary phase cLi2O·dLi x Mn y O z After delithiation, the contained manganese compounds react with the main phase LiNi. a M b O2 can form ternary active materials, which can give ternary composite materials high energy density.

[0031] In the embodiment, the main phase LiNi a M b In O2, 0.6 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.40, and further 0.8 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.30; M includes at least one element selected from cobalt, magnesium, titanium, and aluminum. Through control and optimization of the types of elements indicated by M, these elements, together with nickel, form the main phase LiNi. a M b O2 improves the energy density and electrode potential of high-nickel ternary materials.

[0032] In the embodiments, based on the aforementioned main phase LiNi a M b The metal element M in O2 can be at least one of the following combinations: M includes both cobalt and magnesium; M includes both cobalt and aluminum; or M includes both cobalt and molybdenum. By selecting and controlling the type of metal element M, the formation of the main phase LiNi between metal element M and nickel can be improved. a M b The energy density and electrode potential of O2 are improved, thereby enhancing the electrochemical properties of the high-nickel ternary material in the embodiments of this application.

[0033] In the embodiments, the secondary phase cLi₂O·dLi contained in the lithium-rich manganese composite material x Mn y O z In the given condition, 0.01≤c≤0.2, 0.5≤d≤4.5, 0.5≤x≤5.5, 0.2≤y≤2.2, 0.8≤z≤6.8, further defined as 0.1≤c≤0.2, 2.5≤d≤4.5, 3≤x≤5.5, 1.2≤y≤2.2, 3≤z≤6.8. This is because the manganese-containing portion of the lithium-rich manganese composite material is in the form of cLi₂O·dLi (a secondary phase). x Mn y O z The form exists, this secondary phase cLi2O·dLi x Mn y O z It acts as a lithium replenishing additive, supplementing the lithium ions consumed during the formation of the SEI film in the first charge-discharge process, thus improving the battery's initial coulombic efficiency. Simultaneously, this secondary phase cLi₂O·dLi x Mn y O z During and after delithiation, manganese oxides can react with the main phase LiNi. a M b O2 forms a high-nickel ternary active material, which endows the lithium-rich manganese composite material of the present application with high lithium replenishment effect, as well as the electrode material activity of high-nickel ternary active material. This gives the lithium-rich manganese composite material high energy density, high lithium replenishment stability and lithium replenishment effect, as well as storage performance, and high capacity retention and high cycle performance.

[0034] In the embodiments, the secondary phase is doped into the main phase. This doping should not be understood as physical mixing, but rather as lattice doping. Specifically, the main phase and the secondary phase can be integrally formed during sintering and lattice formation, thereby fully utilizing the respective functions of the main and secondary phases and enhancing the synergistic effect between the two phases. This improves the lithium replenishment effect, energy density, retention rate, and cycle performance of the lithium-rich manganese composite material of the present application embodiments, while also improving its lithium replenishment stability and storage performance.

[0035] In the embodiment, the main phase LiNi a M b The morphology of O2 can be controlled as needed, such as particles or other morphologies. Preferably, the main phase is LiNi. a M b O2 has a particulate morphology, which can be primary or secondary particles. For example, the main phase LiNi... a M b O2 particles have a particle morphology with a particle size of 1-9 μm. For example, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, and 9 μm. During their research, the inventors of this application discovered that the main phase, LiNi... a M b When the particle size of O2 is less than 1 μm, the main phase LiNi a M b O2 particles are small, have a large specific surface area, and are highly reactive, which can easily lead to performance failure and degradation. Meanwhile, the main phase LiNi... a M b When the particle size of O2 is greater than 10 μm, the particles are too large, resulting in a long lithium-ion migration path that causes kinetic polarization problems and insufficient capacity utilization. However, the LiNi main phase provided in the embodiments of this application... a M b Within the particle size range of O2, the BET specific surface area of ​​lithium-rich manganese composite materials can be 0.1-20 μm. 2 / g ensures that lithium-rich manganese composite materials can fully utilize their advantages, such as high lithium replenishment and high capacity retention.

[0036] In the embodiments, the secondary phase cLi₂O·dLi x Mn y O z The morphology can be controlled as needed, such as particles or other morphologies. Preferably, the secondary phase cLi₂O·dLi x Mn y O z The morphology is that of primary or secondary particles. The secondary phase cLi₂O·dLi x Mn y O zThe particles have a particle morphology with a particle size of 0.5-2 μm, for example, 0.5 μm, 0.7 μm, 0.9 μm, 1.1 μm, 1.3 μm, 1.5 μm, 1.7 μm, and 2 μm. During their research, the inventors of this application discovered that the secondary phase cLi₂O·dLi... x Mn y O z When the particle size is less than 0.5 μm, the cLi₂O·dLi of the secondary phase... x Mn y O z Small particle size and excessively large specific surface area result in high activity, which can easily lead to performance failure and degradation. Meanwhile, the secondary phase cLi₂O·dLi x Mn y O z When the particle size is greater than 2 μm, the particles are too large, and the increased lithium-ion migration path leads to kinetic polarization problems, resulting in insufficient capacity utilization. However, the cLi₂O·dLi secondary phase provided in the embodiments of this application... x Mn y O z Within a certain particle size range, the BET specific surface area of ​​lithium-rich manganese composite materials can be 0.1-20 μm. 2 / g ensures that lithium-rich manganese composite materials can fully utilize their advantages, such as high lithium replenishment and high capacity retention.

[0037] In the embodiments, with the total mass of the main phase and the secondary phase being 100%, and the percentage content of the secondary phase being 1-15%, then the percentage content of the main phase is 85-99%. By controlling and optimizing the ratio of the secondary phase to the main phase, the synergistic effect between the main phase and the secondary phase is enhanced while fully utilizing their respective functions. This improves the lithium replenishment effect, energy density, retention rate, and cycle performance of the lithium-rich manganese composite material of this application, while also improving its lithium replenishment stability and storage performance. In specific embodiments, the percentage content of the secondary phase can be, but is not limited to, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, and 15%.

[0038] In the embodiment, the main phase LiNi a M b O2 and cLi2O·dLi doped in the secondary phase of the main phase x Mn y O z The lithium-rich manganese composite material also includes an electronic conductor encapsulation layer coated on the surface of the core, which significantly improves the LiNi content of the main phase. a M b O2 and secondary phase cLi2O·dLi x Mn y Oz The conductivity of the electronic conductor encapsulation layer is improved, reducing the internal resistance of the lithium-rich manganese composite material. The material of this electronic conductor encapsulation layer can be a material that promotes improved electronic conductivity. Specifically, the material of the electronic conductor encapsulation layer can include at least one of carbon, polyaniline, polypyrrole, polyethylene oxide, and poly3,4-ethyldioxythiophene. When the material of the electronic conductor encapsulation layer is carbon, the carbon material can include at least one of amorphous carbon, carbon nanotubes, graphite, carbon black, and graphene. By selecting the appropriate material for the electronic conductor encapsulation layer, the electronic conductivity of the electronic conductor encapsulation layer can be further improved.

[0039] In the embodiments, the electronic conductor encapsulation layer accounts for 1wt%-5wt% of the total mass of the lithium-rich manganese composite material, more specifically 2wt%-3wt%. The thickness of the electronic conductor encapsulation layer is 1-200nm, more specifically 5-100nm. The thickness and percentage of the electronic conductor encapsulation layer can be adjusted as needed, which is beneficial to both the stability of the manganese cathode lithium replenishment material and electron conduction.

[0040] The second aspect of this application provides a method for preparing a lithium-rich manganese composite material, comprising the following steps:

[0041] S10: According to the main phase LiNi a M b Ni, M (represented by the element), and cLi₂O·dLi in O₂ x Mn y O z The stoichiometry of Mn in the sample provides a source of nickel, a source of manganese, and a source of M-containing metals.

[0042] S20: A ternary precursor containing manganese and nickel is obtained by mixing a nickel source, a manganese source, a metal source containing M, and a lithium source.

[0043] S30: A ternary precursor containing manganese and nickel is sintered in a protective atmosphere and then ground with Li2O to obtain a lithium-rich manganese composite material.

[0044] The method for preparing lithium-rich manganese-based composite materials provided in this application involves first mixing a nickel source, a manganese source, a metal source containing M, and a lithium source to obtain a manganese-nickel ternary precursor. Then, the manganese-nickel ternary precursor is sintered in a protective atmosphere, followed by grinding with Li₂O to obtain a manganese-containing cathode lithium replenishment material. This preparation method is simple, easy to control, low-cost, and suitable for large-scale production. Furthermore, the resulting lithium-rich manganese-based composite material exhibits good material uniformity, high energy density, high capacity retention, good lithium replenishment stability, and stable cycle performance.

[0045] In step S10, according to the molecular formula LiNi a Mb The elements Ni and M shown in O2 and the molecular formula cLi₂O·dLi x Mn y O z The stoichiometric ratio of Mn in the formula provides a nickel source, a manganese source, and a metal source containing M. For example, the nickel source may include at least one of nickel oxide, nickel nitrate, nickel chloride, nickel hydroxide, nickel acetate, and nickel hydroxide. The manganese source may include at least one of manganese tetroxide, manganese dioxide, and manganese oxide. The metal source containing M may include at least one of cobalt, manganese, magnesium, titanium, and aluminum sources. For example, the cobalt source may include at least one of cobalt oxide, cobalt nitrate, cobalt chloride, cobalt hydroxide, cobalt acetate, and cobalt carbonate; the magnesium source may include at least one of magnesium nitrate, magnesium sulfate, or magnesium chloride; the titanium source may include at least one of titanium dioxide and titanium chloride; the aluminum source may include at least one of aluminum oxide, aluminum nitrate, aluminum chloride, aluminum hydroxide, aluminum acetate, and aluminum hydroxide; the iron source may include at least one of iron oxide, iron nitrate, iron chloride, iron hydroxide, iron acetate, and iron oxalate; the vanadium source may include at least one of vanadium pentoxide and vanadium oxynitrate; and the molybdenum source may include at least one of molybdenum trioxide, molybdenum dioxide, molybdenum carbonate, molybdenum formate, and molybdenum acetate.

[0046] In step S20, the lithium source includes at least one of lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, lithium oxide, and lithium oxalate. The method for mixing the nickel source, manganese source, M-containing metal source, and lithium source includes: placing the nickel source, manganese source, M-containing metal source, and lithium source in a centrifugal mixer for mixing.

[0047] In step S30, the protective atmosphere is an oxygen-argon mixture, and the volume concentration ratio of oxygen to argon is (90-98):(2-10). In the embodiment, the sintering temperature is 600-800℃, and more preferably 700-800℃, and the time should be sufficient, such as 12-24h, and more preferably 18-24h. By controlling the sintering temperature and time, the ternary precursor containing manganese nickel can be sintered with a lithium source to form the main phase LiNi. a M b O2 and Li contained in the secondary phase x Mn y O z The main phase of LiNi a M b O2 and Li contained in the secondary phase x Mn y O z The main phase LiNi was obtained by grinding with Li2O. a M b O2 and secondary phase cLi2O·dLi x Mn y Oz .

[0048] In the embodiment, the main phase LiNi a M b O2 and cLi2O·dLi doped in the secondary phase of the main phase x Mn y O z After step S30 above, the formation of the nucleus further includes coating the surface of the nucleus with an electronic conductor encapsulation layer, that is, on the LiNi of the main phase. a M b O2 and secondary phase cLi2O·dLi x Mn y O z The surface of the formed core is coated with an electronic conductor encapsulation layer. Specifically, the appropriate method for forming the electronic conductor encapsulation layer can be flexibly selected based on the material of the encapsulation layer. For example, depending on the material properties of the encapsulation layer, in-situ coating followed by sintering can be used, or physical deposition, chemical deposition, and other methods can be employed.

[0049] A third aspect of this application provides a positive electrode sheet, including a positive current collector and a positive active layer bonded to the surface of the positive current collector. The positive active layer contains a lithium-rich manganese composite material provided in this application, or a lithium-rich manganese composite material prepared by the preparation method of the lithium-rich manganese composite material provided in this application.

[0050] The positive electrode provided in this application contains the lithium-rich manganese composite material provided in this application, or the lithium-rich manganese composite material prepared by the preparation method of the lithium-rich manganese composite material provided in this application. Therefore, the positive electrode of this application has high energy density, lithium replenishment function, high cycle performance and long life.

[0051] A fourth aspect of this application provides a secondary battery, including a positive electrode and a negative electrode, wherein the positive electrode is the positive electrode provided in this application.

[0052] The secondary battery provided in this application embodiment contains the electrode sheet of this application. Therefore, the secondary battery of this application has excellent first coulombic efficiency, high energy density and cycle performance, high capacity retention, long life and stable electrochemical performance.

[0053] The following description is based on specific embodiments.

[0054] Example 1

[0055] This embodiment provides a lithium-rich manganese composite material and its preparation method.

[0056] The lithium-rich manganese composite material includes a main phase LiNi. 0.8 Co 0.1Mg 0.1 O2 and a secondary phase 0.01Li2O·Li2MnO2 doped within the main phase. The total mass of the main and secondary phases is 100%, with the secondary phase 0.01Li2O·Li2MnO2 comprising 1% and the main phase LiNi... 0.8 Co 0.1 Mg 0.1 The O2 content is 99%.

[0057] The preparation method of this lithium-rich manganese composite material includes the following steps:

[0058] S10: Provides nickel oxide, cobalt oxide, magnesium oxide, and manganese oxide according to the molar ratio of Ni, Co, Mg, and Mn elements of 0.792:0.099:0.099:0.01;

[0059] S20: Nickel oxide, cobalt oxide, manganese oxide, magnesium oxide and lithium carbonate are mixed in a centrifugal mixer to obtain a ternary precursor containing manganese and nickel;

[0060] S30: A ternary precursor containing manganese and nickel was sintered for 12 hours in a protective atmosphere with an oxygen to argon volume concentration ratio of 98:2 and a temperature of 800°C. Then, it was mechanically ground with Li₂O to obtain a secondary phase of 0.01Li₂O·Li₂MnO₂ doped into the main phase LiNi. 0.8 Co 0.1 Mg 0.1 Lithium-rich manganese composite materials in O2.

[0061] Testing revealed that the manganese-containing cathode lithium supplement material has a particle size of 2.35 μm and a BET specific surface area of ​​0.46 m². 2 / g.

[0062] Example 2

[0063] This embodiment provides a lithium-rich manganese composite material and its preparation method.

[0064] The lithium-rich manganese composite material includes a main phase LiNi. 0.8 Co 0.1 Mg 0.1 O2 and a secondary phase 0.01Li2O·Li2MnO3 doped within the main phase. The total mass of the main and secondary phases is 100%, with the secondary phase 0.01Li2O·Li2MnO3 comprising 5% and the main phase LiNi... 0.8 Co 0.1 Mg 0.1 The O2 content is 95%.

[0065] The preparation method of this lithium-rich manganese composite material can be referred to the steps of Example 1. The difference from Example 1 is that in step S10 of this Example 1, nickel oxide, cobalt oxide, magnesium oxide and manganese oxide are provided according to the molar ratio of Ni, Co, Mg and Mn elements of 0.76:0.095:0.095:0.05.

[0066] Testing revealed that the manganese-containing cathode lithium supplement material has a particle size of 2.35 μm and a BET specific surface area of ​​0.46 m². 2 / g.

[0067] Example 3

[0068] This embodiment provides a lithium-rich manganese composite material and its preparation method.

[0069] The lithium-rich manganese composite material includes a main phase LiNi. 0.8 Co 0.1 Mg 0.1 O2 and a secondary phase 0.02Li2O·Li6MnO4 doped within the main phase. The total mass of the main and secondary phases is 100%, with the secondary phase 0.02Li2O·Li6MnO4 comprising 10% and the main phase LiNi... 0.8 Co 0.1 Mg 0.1 The O2 content is 90%.

[0070] The preparation method of this lithium-rich manganese composite material can be referred to the steps of Example 1. The difference from Example 1 is that in step S10 of Example 1, nickel oxide, cobalt oxide, magnesium oxide and manganese oxide are provided according to the molar ratio of Ni, Co, Mg and Mn elements of 0.72:0.09:0.09:0.1.

[0071] Example 4

[0072] This embodiment provides a lithium-rich manganese composite material and its preparation method.

[0073] The lithium-rich manganese composite material includes a main phase LiNi. 0.8 Co 0.1 Mg 0.1 O2 and a secondary phase 0.02Li2O·Li6MnO4 doped within the main phase. The total mass of the main and secondary phases is 100%, with the secondary phase 0.02Li2O·Li6MnO4 comprising 15% and the main phase LiNi... 0.8 Co 0.1 Mg 0.1 The O2 content is 85%.

[0074] The preparation method of this lithium-rich manganese composite material can be referred to the steps of Example 1. The difference from Example 1 is that in step S10 of Example 1, nickel oxide, cobalt oxide, magnesium oxide and manganese oxide are provided according to the molar ratio of Ni, Co, Mg and Mn elements of 0.68:0.085:0.085:0.15.

[0075] Example 5

[0076] This embodiment provides a lithium-rich manganese composite material and its preparation method.

[0077] The lithium-rich manganese composite material includes a main phase LiNi. 0.8 Co 0.15 Al 0.05 O2 and the secondary phase 0.2Li2O·2Li doped within the main phase 2.3 Mn 0.5 O 1.9 Of which, taking the total mass of the primary and secondary phases as 100%, the secondary phase is 0.2Li₂O·2Li. 2.3 Mn 0.5 O 1.9 The percentage content is 10%, with LiNi as the main phase. 0.8 Co 0.15 Al 0.05 The O2 content is 90%.

[0078] The preparation method of this lithium-rich manganese composite material includes the following steps:

[0079] S10: Provides nickel oxide, cobalt oxide, manganese oxide, and aluminum oxide according to the molar ratio of Ni, Co, Mn, and Al elements of 0.72:0.135:0.1:0.045;

[0080] S20: Nickel oxide, cobalt oxide, manganese oxide, aluminum oxide and lithium carbonate are mixed in a centrifugal mixer to obtain a ternary precursor containing manganese and nickel;

[0081] S30: A ternary precursor containing manganese and nickel was sintered for 12 hours in a protective atmosphere with an oxygen to argon volume concentration ratio of 98:2 and at 800°C. Then, it was mechanically ground with Li₂O to obtain the secondary phase 0.2Li₂O·2Li. 2.3 Mn 0.5 O 1.9 Doped in the main phase LiNi 0.8 Co 0.15 Al 0.05 Lithium-rich manganese composite materials in O2.

[0082] Example 6

[0083] This embodiment provides a lithium-rich manganese composite material and its preparation method.

[0084] The lithium-rich manganese composite material includes a main phase LiNi. 0.8 Co 0.1 Mg 0.1 O2 and a secondary phase 0.02Li2O·Li6MnO4 doped within the main phase are present, forming a core. A carbon coating layer covers the core's surface. The total mass of the main and secondary phases is 100%, with the secondary phase 0.02Li2O·Li6MnO4 comprising 10% and the main phase LiNi... 0.8 Co 0.1 Mg 0.1 The O2 content is 90%.

[0085] The preparation method of this lithium-rich manganese composite material includes the following steps:

[0086] S10: Provides nickel oxide, cobalt oxide, magnesium oxide, and manganese oxide according to the molar ratio of Ni, Co, Mg, and Mn elements of 0.72:0.09:0.09:0.1;

[0087] S20: Nickel oxide, cobalt oxide, magnesium oxide, manganese oxide and lithium carbonate are mixed in a centrifugal mixer to obtain a ternary precursor containing manganese and nickel;

[0088] S30: A ternary precursor containing manganese and nickel was sintered for 12 hours in a protective atmosphere with an oxygen to argon volume concentration ratio of 98:2 and a temperature of 800°C. Then, it was mechanically ground with Li₂O to obtain a secondary phase of 0.01Li₂O·Li₂MnO₂ doped into the main phase LiNi. 0.8 Co 0.1 Mg 0.1 Lithium-rich manganese composite materials in O2;

[0089] S30: The lithium-rich manganese composite material obtained in step S30 and the carbon source are mixed in a centrifugal mixer to obtain a lithium-rich manganese composite material containing a carbon coating layer.

[0090] Testing revealed that the manganese-containing cathode lithium supplement material has a particle size of 2.35 μm and a BET specific surface area of ​​0.46 m². 2 / g.

[0091] Comparative Example 1

[0092] This comparative example provides an existing commercially available high-nickel ternary material, namely LiNi. 0.8 Co 0.1 Mn 0.1 O2. Compared with Examples 1-4, the high-nickel ternary material in this comparative example does not contain secondary phases.

[0093] Comparative Example 2

[0094] This comparative example provides an existing commercially available high-nickel ternary material, namely LiNi. 0.6 Co 0.2 Mn 0.2 O2. Compared with Example 5, the high-nickel ternary material in this comparative example does not contain the secondary phase 0.02Li2O·Li2MnO2.

[0095] Comparative Example 3

[0096] This comparative example provides an existing commercially available high-nickel ternary material, namely LiNi. 0.8 Co 0.15 Al 0.05 O2. Compared with Example 6, the high-nickel ternary material in this comparative example does not contain secondary phase 0.2Li2O·2Li. 2.3 Mn 0.5 O 1.9 .

[0097] Comparative Example 4

[0098] This comparative example provides a ternary material composed of a commercially available high-nickel ternary material and Li2MnO2 through physical mixing. The high-nickel ternary material is LiNi. 0.8 Co 0.1 Mg 0.1 O2.

[0099] 2. Example of a lithium-ion battery:

[0100] The lithium-rich manganese composite materials provided in Examples 1 to 6 and the high-nickel ternary materials provided in Comparative Examples 1 to 4 were assembled into positive electrode electrodes and lithium-ion batteries respectively according to the following methods:

[0101] Positive electrode: Under the same conditions, the positive electrode material, polyvinylidene fluoride and SP-Li were mixed and ball-milled at a mass ratio of 95:3:2 to obtain a positive electrode slurry. The positive electrode slurry was coated on the surface of aluminum foil, rolled, and vacuum dried overnight at 110°C to obtain a positive electrode sheet. The positive electrode materials were the lithium-rich manganese composite materials provided in Examples 1-7, the high-nickel ternary materials provided in Comparative Examples 1-3, and the ternary materials provided in Comparative Example 4.

[0102] Negative electrode: Lithium metal sheet;

[0103] Electrolyte: Ethyl carbonate and ethyl methyl carbonate are mixed in a volume ratio of 3:7, and LiPF6 is added to form an electrolyte with a concentration of 1 mol / L.

[0104] Diaphragm: Polypropylene microporous diaphragm;

[0105] Lithium-ion battery assembly: The lithium metal sheet-separator-electrolyte-positive electrode structure is assembled into a lithium-ion battery in an inert atmosphere glove box.

[0106] 3. Example of lithium-ion battery performance testing:

[0107] The electrochemical performance of each lithium-ion battery assembled in the above lithium-ion battery examples was tested under the following conditions:

[0108] The assembled batteries were subjected to charge-discharge tests at room temperature, with charge-discharge voltages ranging from 2.7V to 4.3V. The electrochemical performance of the lithium secondary batteries containing Examples 1-6 and Comparative Examples 1-4 is shown in Table 1.

[0109] Table 1

[0110]

[0111] As shown in Table 1, the lithium-rich manganese composite materials in Examples 1-6 of this application exhibit a significantly improved specific capacity compared to the comparative example due to the synergistic effect between the main phase and the secondary phase. The secondary phase effectively compensates for the active lithium ions consumed during the first charge and discharge cycle due to the formation of the SEI film, thereby increasing the initial capacity and improving the cycle stability of the battery. Furthermore, after delithiation, the contained manganese forms a ternary active material with nickel and other metals, thus exhibiting the activity of a ternary active material. Example 6 further optimizes its performance by coating the core surface of the main phase and the secondary phase doped within the main phase with carbon, resulting in a significantly improved specific capacity compared to Example 3.

[0112] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A lithium-rich manganese-based composite material, characterized in that, The lithium-rich manganese composite material includes LiNi as the main phase. a M b O2 and cLi2O·dLi as a secondary phase x Mn y O z The secondary phase is doped into the main phase; wherein, the LiNi a M b In O2, 0.6 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.40, and M is the metal element contained in the ternary active material. The cLi2O·dLi x Mn y O z In the formula, 0.01≤c≤0.2, 0.5≤d≤4.5, 0.5≤x≤5.5, 0.2≤y≤2.2, 0.8≤z≤6.8; M does not contain manganese, and M includes at least one element selected from cobalt, magnesium, titanium, and aluminum; the main phase is LiNi a M b O2 and cLi2O·dLi doped in the secondary phase of the main phase x Mn y O z Formation of the nucleus, secondary phase cLi₂O·dLi x Mn y O z After delithiation, the manganese oxide in this secondary phase reacts with the LiNi in the main phase. a M b O2 forms a ternary active material NCM; the preparation method of the lithium-rich manganese composite material includes the following steps: According to the main phase LiNi a M b The elements Ni and M shown in O2 and the cLi2O·dLi of the aforementioned secondary phase x Mn y O z The stoichiometry of Mn in the sample provides a source of nickel, a source of manganese, and a source of M-containing metals. The nickel source, the manganese source, the M-containing metal source, and the lithium source are mixed to obtain a ternary precursor containing manganese and nickel. The manganese-nickel-containing ternary precursor was sintered in a protective atmosphere and then ground with Li2O to obtain the lithium-rich manganese composite material.

2. The lithium-rich manganese composite material as described in claim 1, characterized in that, With the total mass of the primary phase and the secondary phase being 100%, the percentage content of the secondary phase is 1-15%.

3. The lithium-rich manganese composite material as described in claim 1, characterized in that, The main phase LiNi a M b O2 has a particle morphology with a particle size of 1-9 μm; and / or The secondary phase cLi2O·dLi x Mn y O z The particles have a particle morphology with a particle size of 0.5-2 μm; and / or The BET specific surface area of ​​the lithium-rich manganese composite material is 0.1-20 μm. 2 / g.

4. The lithium-rich manganese composite material as described in claim 1, characterized in that, The lithium-rich manganese composite material also includes an electronic conductor encapsulation layer covering the surface of the core.

5. The lithium-rich manganese composite material as described in claim 4, characterized in that, The electronic conductor encapsulation layer accounts for 1 wt%-5 wt% of the total mass of the lithium-rich manganese composite material; and / or The thickness of the electronic conductor encapsulation layer is 1-200 nm; and / or The material of the electronic conductor encapsulation layer includes at least one of carbon, polyaniline, polypyrrole, polyethylene oxide, and poly3,4-ethyldioxothiophene.

6. The lithium-rich manganese composite material as described in claim 1, characterized in that, The protective atmosphere is an oxygen-argon mixture, and the volume concentration ratio of oxygen to argon is (90-98):(2-10).

7. The lithium-rich manganese composite material as described in claim 1, characterized in that, The sintering process is carried out at a temperature of 600-800℃ for 12-24 hours.

8. A positive electrode sheet, comprising a positive current collector and a positive active layer bonded to the surface of the positive current collector, characterized in that: The positive electrode active layer contains the lithium-rich manganese composite material according to any one of claims 1-7.

9. A secondary battery, comprising a positive electrode and a negative electrode, characterized in that: The positive electrode is the positive electrode as described in claim 8.

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